My first build, Ballerina

[Martin Harris - Moderator]

It’s quite possible that the anomaly on the plan is simply due to the limitations of drawing a 3D item in 2D. 
 

When I built a similar design (Ohmen) recently I didn’t even build the fuselage over the plan - marking the former positions and building it initially on a machine table with various squares for alignment. As per advice above, the rear formers were added after accurately aligning and joining the tail - perhaps the sides would have shown a similar mismatch on the plan?

[Steve Goodwin]

So bits and pieces have arrive so I can continue with the build, before I glue in f1 and f2 I am considering the battery hatch and access. On other build blogs, the 1/4 hardwood spar that spans f1 / f2 can form part of the hatch, I am a little concerned that this may weaken the structure, considering it is one of the strongest single pieces of material used in this area of the fuselage.

[EarlyBird]

10 minutes ago, Steve Goodwin said:

the 1/4 hardwood spar that spans f1 / f2

There is no hardwood spar.

[EarlyBird]

I added 1/4 balsa to each side.

also the battery tray spans F1/F2 which adds strength.

 

[EarlyBird]

Found a picture.

 

[Steve Goodwin]

1 hour ago, EarlyBird said:

There is no hardwood spar.

I’m concerned about removing the hardwood spar as shown here on Peter’s original build

[EarlyBird]

Hmm it's balsa. I have always thought that the main function of the spars was for sheeting to glue to. 

Interestingly on Peter's Hound Dog.

Which I am about to copy on my Ohmen.?

I therefore conclude that there is no problem strength wise. My Ballerina is very strong, I have tested it, don't ask how.

 

[Steve Goodwin]

Thanks EB, makes more sense now ?

[kc]

Putting in a liteply tray to hold lipo will replace any lost strength.   I have found it's so easy to cut holes into liteplay tray for connector and velcro straps BEFORE fitting and a lot harder after!   I cut spare holes in case lipo goes in wires front or wires back.  ( Liteply can be cut with a stanley knife)

[Steve Goodwin]

Progress so far. It’s all gone fairly well, I made a mistake of fitting F4 too high, so the cockpit floor is in two sections, schoolboy error but it does not seem to of effected the squareness of the fuselage 

[Steve Goodwin]

F2 has been cut to allow for the battery tray, and a new piece of balsa cut for F3 as the supplied F3 will form part of the battery tray, which is next to be built. Very pleased with the alignment so far, the tail platform is spot on and a dry fit of the snake litres has not required any further adjustment to the holes in the formers.

[EarlyBird]

Looking good.

Mentioning snakes has reminded me of an error I made, I glued them in to all the formers ?. Not a major issue I just have to keep retrimming every flight as the temperature changes.

 

[Graham Davies 3]

Looking good Steve.

 

We'll be able to work on some synchronised Ballerina routines!

 

Graham

[Steve Goodwin]

3 hours ago, EarlyBird said:

Looking good.

Mentioning snakes has reminded me of an error I made, I glued them in to all the formers ?. Not a major issue I just have to keep retrimming every flight as the temperature changes.

 

Thanks for the heads up EB, how should they be fixed? I was thinking just at the exit of the fuselage

[Graham Davies 3]

Secure at both ends Steve. Not in the middle. That results in BOTH parts expanding and cancelling out any trim changes. If you secure them all along, the outer cannot 'bow' to allow it to expand, and there is a 'net' increase in the relative length of the inner. 

 

I hope that helps

 

Graham

[kc]

Steve,  in another thread there is mention of the hole for wing dowel in F2 being rather low ( Peter's original plan was correct while magazine plan was not )  - have you had a chance to see if the cut part is going to line up with the wing rib dowel slots?   Even if it lines up it could need reinforcement of F2 as the hole might be very close to edge.

Thought it worth mentioning this before it's too late!

Edited September 8, 2021 by kc

[EarlyBird]

KC on the Sarik plan the bottom of the hole to the bottom of the former is 4mm, which worked for me without any adjustment.

[Steve Goodwin]

18 hours ago, kc said:

Steve,  in another thread there is mention of the hole for wing dowel in F2 being rather low ( Peter's original plan was correct while magazine plan was not )  - have you had a chance to see if the cut part is going to line up with the wing rib dowel slots?   Even if it lines up it could need reinforcement of F2 as the hole might be very close to edge.

Thought it worth mentioning this before it's too late!

Hi KC, thanks for the heads up I'll check this today, hopefully I'll be as lucky as EarlyBird ?

[kc]

Well it is 4mm on the pull out plan too but that gives little material to file out to allow wing to fit,  depends on the quality of ply whether that will be strong enough.   On Peter's original hand drawn plan it was 10mm which seems better.  ( the dowel in Peter's drawing is higher in the wing rib too )

I would suggest adding a reinforcing piece of birch ply if in any doubt about the strength in this area.

[Steve Goodwin]

More progress to show those who maybe interested ? so far the build is going great and I am really enjoying it, only a couple of small mistakes, but as a good friend once told me “every day is a school day” how true with building. The forward turtle deck and battery hatch is next, I figured that the hatch is going to get lots of handling so I doubled up on the outer sheeting and braced the internals with some soft balsa, nice and strong and a pretty good fit for a first timer ?

Edited September 13, 2021 by Steve Goodwin

[Steve Goodwin]

Next was the battery tray, nice and easy coffin style with a foam insert for the battery to sit on, quite handy as the tray will sit just above the motor mount threaded rod, I will epoxy this in to give extra strength, not that Ballerina will need it, she’s very strong anyway 

[Steve Goodwin]

Not fitted yet but next will be the securing for the battery hatch. My idea here is to epoxy four small hardwood blocks with small hex head machine screws, about 1-1.5mm below the fuselage sides, along with matching magnets on the hatch, this will allow for and minor adjustments as my hatch does not sit flush on all four corners, one of the learning steps ?

 

Edited September 13, 2021 by Steve Goodwin

[Steve Goodwin]

Not really sure what happened to the cockpit, but I am very pleased with my work around, this the first time I have attempted to bend and shape balsa outside of its natural limits, the lines are very tactile and now smooth are better than I could of hoped/wished for.

[Steve Goodwin]

More progress albeit a little slow, but as I mentioned earlier, I am taking my time. The four mounting studs and magnets for the battery hatch were next on the build. I found that this method was perfect for any slight warp or misalignment with the hatch. Although not commonly used together these two materials worked well for this.

 

 

Next was the upper deck stringers, I found this quite fiddly as I wanted the spacing to be accurate, which it's not ?. They will be covered I know, but I still try. The infills looked ok with the little scallop detail, spacing at the rear is nowhere near as neat, but I'm enjoying this more than I thought and I'm learning loads.

 

 

 

Next was the bottom sheeting and epoxied in the wing fixing plate, pretty much as easy as it gets, I am starting to get the feel that things are coming together

 

 

The motor standoffs were next to fit, again pretty straight forward (pardon the pun !!) I used 4mm stud with nylocs and washers either side of F1 and I'll do the same on the motor side. This gives a very strong motor mount and makes the conversion from IC to electric very easy. Notice the extra aperture in F1 to allow for additional cooling for the electronics, my plan is to build an exit ramp and encourage air flow via an outlet near the pilot

 

 

 

I have yet to look at the cowl, as the fillets for the rear control surfaces mount is giving me lots to think about. Fixing the elevator (after covering) to the fuselage before attaching the infill fillets seems to make more sense to me as I will have so much more "real estate" to glue to. I notice that other builders have created a dummy tail and fin and glued 1/4" scrap to F10 and shaped it from this and removing the dummy when complete. I would guess it would then be a case of sliding in the preassembled tail pieces but removing lots of glue in the process?? ? Not sure this gives any wriggle room when it comes to final assembly? Please feel free to chip in ?

 

[kc]

as mentioned in another thread the fillets alongside the fin are sanded to shape using dummy tailplane and fin ( T piece) but of course they are not glued in when sanding!   The fillets can be temporarily fixed to the dummy tailplane & fin T piece with tiny bits of double sided Sellotape.   Too large piece makes removal very difficult so just 1/2 inch lengths will do.   The dummy T piece is probably best pinned to the fuselage whilst sanding.   When shaped the fillets are removed and I prefer to cover them before gluing to fin.   Then tailplane is covered  and eventually glued on glued on to the fuselage when  fus has been covered.  Finally fin with fillets is glued onto tailplane.  Or perhaps glue fin to t/p then add fillets later.  Much easier to cover flat  and unassembled parts!   Thats my way others may have different ideas.......

Edited September 21, 2021 by kc